1. Field of the Invention
The present invention relates to an error detection method and circuit that detect chroma upsampling error and an error reduction method and circuit that detect and reduce chroma up-sampling error.
2. Description of Related Art
FIG. 7 is a view showing an artifact (data error or signal distortion) called chroma upsampling error (CUE). The chroma upsampling error is an error that, because the information amount of a color signal is small with the DVD specifications, color information appears only in every other line if the signal is simply converted into progressive, and particularly, a plane solidly filled with pure red or the like appears like a lattice.
As shown in FIG. 7, if a vertically down-sampled interlaced color-difference signal is mistakenly vertically up-sampled and then converted into progressive, the chroma upsampling error occurs. The artifact has a high frequency component in the vertical direction, which is similar to combing. As shown in FIG. 8, if it is up-sampled within a frame, such a program does not occur.
FIG. 9 is a flowchart showing a chroma upsampling error reduction method according to related art. The error reduction method shown in FIG. 9, for example, has been used for such an artifact. As shown in FIG. 9, the method detects color-difference combing (step S101) and, if the color-difference combing is detected, applies a vertical low-pass filter (step S102) (cf. e.g. Published Japanese Translation of PCT International Publication for Patent Application, No. 2006-500823).